E57 Insufficient Refrigerant Amount Or Detection Of Service Valve Closure - Mitsubishi Heavy Industries MHI FDU71VNXVF1 Technical Manual

Error code
Indoor control PCB
Remote control:
E57
Outdoor control PCB
Outdoor inverter
1. Applicable model
All models
2. Error detection method
• Judge insufficient refrigerant
amount by detecting the
temperature differnce between
indoor heat exchanger (ThI-R)
and indoor return air (ThI-A).
• It detects at initial startup in
cooling or dehumidifying
mode after power ON.
(In case of 71 model it cannot
detect)
3. Condition of Error displayed
Anomalous stop at initial
detection
4. Presumable cause
• Defective indoor heat
exchanger temperature
thermistor
• Defective indoor return air
temperature thermistor
• Defective indoor control PCB
• Insufficient refregerant
amount
Note: Insufficient refrigerant amount preventive control makes compressor stopped, if it judges insufficient refrigerant amount by detecting the
temperature difference between indoor heat exchanger (ThI-R) and return air temperature (ThI-A) for 1 minute after compressor ON in
cooling or dehumidifying mode and for 9 minutes after compressor ON in heating mode. [ in cooling mode: (ThI-A)-(ThI-R)>4degC, in
heating mode: (ThI-R)-(ThI-A)<4degC]
LED Green
Keeps flashing
Keeps flashing
Yellow
PCB
Keeps flashing
5. Troubleshooting
service valve fully
opened?
connections of indoor
heat exchanger and/or return air
temperature thermistor
connectors OK?
characteristics of indoor heat
exchanger and/or return air
temperature thermistor
Is the low
pressure during operation
Indoor heat exchanger, return air temperature thermistor
Temperature-resistance characteristics
(Broken wire)
15
10
5
(Short circuit)
Red
Content
Stays OFF
Insufficient refrigerant amount
1 time flash
or detection of service valve closure
Diagnosis
Is the
NO
YES
Are the
NO
YES
Are the
NO
OK?
YES
NO
normal?
YES
5kΩ at 25°C
0 10 20 30 40 50
Temperature (°C)
178
- -
'12 • PAC-T-178
Countermeasure
Open fully.
Correct indoor heat
exchanger, return air
temperature thermistor
connector connections.
Defective indoor heat
exchanger, return air
temperature thermistor ➞
Replace.
Charge refrigerant.
Defective indoor control
PCB ➞ Replace. (Defective
indoor heat exchanger,
return air temperature
thermistor input circuits)